The French publication FR 26 45 242 discloses a multiple coupling device for hydraulic line connections and electric plug and socket type connections wherein the hydraulic coupling is in the form of a spring-loaded quick-fitting coupling of the ball-locking type. A lower pan-shaped plate with upwardly projecting plug members of the quick-fitting coupling is fixedly mounted on the tractor, while the sleeve members of the coupling connections are mounted on a housing which is engaging the lower pan-shaped plate from above in a cover-like fashion, and including clamping levers which are adapted for rotation about a common axis, said clamping levers being provided with arcuate slots for engagement with clamping studs which are laterally projecting from the lower plate and which are equipped with rollers.
The upper box-like housing has an upper fixed plate from which the sleeve members of the quick-fitting coupling project downwardly so as to extend through a second plate which is movable relative to the upper fixed plate and which is connected with the sliding bushings of the sleeve members for the ball locking mechanism. This second movable intermediate plate is mounted for reciprocating movement in vertical laterally arranged slots on the box-like housing, and is adapted, by way of arcuate tracks on the lateral clamping levers, for movement, upon each coupling and decoupling action, relative to the upper fixed plate in such a manner that the ball locking mechanisms of the sleeve members are engaging into corresponding peripheral keyways provided in the plug-in members or are being disengaged therefrom.
The disadvantage of this prior art multiple coupling is that, with each coupling and decoupling event, hydraulic fluid is escaping on the quick-fitting couplings which collects in the fixedly mounted pan-shaped lower member. Therefore, the multiple coupling cannot be mounted onto the vehicle in a position that varies from the lower dish-shaped plate. Furthermore, because of the additional movable plate needed for the operation of the ball locking mechanisms, the design of this coupling is relatively complex, and the sleeve members of the quick-fitting couplings cannot be mounted onto the cover-like upper portion with sufficient rigidity so as to ensure a reliable wear-resistant connection. For instance, flexible pipes or hoses containing pressurized fluid may cause displacement or misalignment between the plug members and the sleeve members of the couplings and may adversely affect the function of the same. Furthermore, a precise mutual positioning of the two movable plates of the multiple coupling must be assured by the lever system.
According to another prior art quick-fitting coupling for coupling members equipped with valves, which is disclosed in the German Publication DE-AS 12 56 006, each of the two clamping levers is provided with an arcuate track which terminates in a catch for receiving clamping studs that project from the oppositely positioned support plate. Furthermore, parallel oriented guide pins are extending from the lower support plate adjacent to the sleeve members of the valve couplings. The guide pins are adapted for engagement, with relatively little play, into corresponding recesses provided on the other support plate with the plug members. However, in this arrangement the sleeve members extend relatively high up from the lower support member, which makes this coupling rather bulky, and there is also the disadvantage that the hydraulic fluid leaking out after each coupling and decoupling operation is causing the coupling to be contaminated and therefore necessitates frequent cleaning which is relatively cumbersome.
German Publication DE 32 28 434 describes a coupling device for the energy supply to interchangeable working units of an injection molding machine which is equipped with so-called quick-locking couplings, with the coupling members being comprised of a pin bushing and a pin which is adapted for axial insertion therein. The locking means are in the form of locking balls which engage into a peripheral groove of the pin and which are retained in the engaged position by a locking sleeve which is axially movable against the bias of a spring. This locking sleeve must be separately actuated during each coupling and decoupling procedure. Furthermore, this prior art coupling device is not equipped with manually operable pivoting levers for putting the members into the coupled position. Instead, the coupling procedure for all couplings is done simultaneously by means of an unduly complicated piston and cylinder arrangement which is controlled, for instance, hydraulically and automatically from a control desk, so that the coupling procedure is taking place fully automatically without any additional manual manipulation.
Another multiple coupling with a plurality of self-sealing interlocking coupling members has been disclosed in German Publication DE- 39 18 250 A1. In this coupling device, either all plug-in members and/or all bushing members are being retained, respectively, in a mounting plate adjacent to the connecting housing with a relatively large lateral play transversely to the axial centerline of respective coupling, and allowance is made for some limited sliding movement. However, this lateral play during the coupling procedure causes difficulties when the respective plug-in and bushing members are connected with flexible pipes or hoses, as was already pointed out earlier in connection with the French Publication FR 26 45 242.